diff --git a/app/modules/services/templates/services/catalogue_list.html b/app/modules/services/templates/services/catalogue_list.html
index 7d9714a..a3b4855 100644
--- a/app/modules/services/templates/services/catalogue_list.html
+++ b/app/modules/services/templates/services/catalogue_list.html
@@ -137,7 +137,7 @@
       <div class="flex flex-wrap items-center justify-end gap-2" aria-label="Service catalogue pagination">
         <form method="get">
           <input type="hidden" name="q" value="{{ q }}">
-          <input type="hidden" name="category_id" value="{{ category_id or '' }}">
+          {% if category_id %}<input type="hidden" name="category_id" value="{{ category_id }}">{% endif %}
           <input type="hidden" name="recurrence_type" value="{{ recurrence_type }}">
           <input type="hidden" name="engagement_type" value="{{ engagement_type }}">
           <input type="hidden" name="per_page" value="{{ per_page }}">
@@ -150,7 +150,7 @@
 
         {% if first_page > 1 %}
         <form method="get">
-          <input type="hidden" name="q" value="{{ q }}"><input type="hidden" name="category_id" value="{{ category_id or '' }}"><input type="hidden" name="recurrence_type" value="{{ recurrence_type }}"><input type="hidden" name="engagement_type" value="{{ engagement_type }}"><input type="hidden" name="per_page" value="{{ per_page }}"><input type="hidden" name="page" value="1">
+          <input type="hidden" name="q" value="{{ q }}">{% if category_id %}<input type="hidden" name="category_id" value="{{ category_id }}">{% endif %}<input type="hidden" name="recurrence_type" value="{{ recurrence_type }}"><input type="hidden" name="engagement_type" value="{{ engagement_type }}"><input type="hidden" name="per_page" value="{{ per_page }}"><input type="hidden" name="page" value="1">
           <button class="rounded-lg border border-slate-300 px-3 py-2 text-sm font-medium text-slate-700 hover:bg-slate-50">1</button>
         </form>
         {% if first_page > 2 %}<span class="px-1 text-slate-400">…</span>{% endif %}
@@ -159,7 +159,7 @@
         {% for page_number in range(first_page, last_page + 1) %}
         <form method="get">
           <input type="hidden" name="q" value="{{ q }}">
-          <input type="hidden" name="category_id" value="{{ category_id or '' }}">
+          {% if category_id %}<input type="hidden" name="category_id" value="{{ category_id }}">{% endif %}
           <input type="hidden" name="recurrence_type" value="{{ recurrence_type }}">
           <input type="hidden" name="engagement_type" value="{{ engagement_type }}">
           <input type="hidden" name="per_page" value="{{ per_page }}">
@@ -171,14 +171,14 @@
         {% if last_page < pages %}
         {% if last_page < pages - 1 %}<span class="px-1 text-slate-400">…</span>{% endif %}
         <form method="get">
-          <input type="hidden" name="q" value="{{ q }}"><input type="hidden" name="category_id" value="{{ category_id or '' }}"><input type="hidden" name="recurrence_type" value="{{ recurrence_type }}"><input type="hidden" name="engagement_type" value="{{ engagement_type }}"><input type="hidden" name="per_page" value="{{ per_page }}"><input type="hidden" name="page" value="{{ pages }}">
+          <input type="hidden" name="q" value="{{ q }}">{% if category_id %}<input type="hidden" name="category_id" value="{{ category_id }}">{% endif %}<input type="hidden" name="recurrence_type" value="{{ recurrence_type }}"><input type="hidden" name="engagement_type" value="{{ engagement_type }}"><input type="hidden" name="per_page" value="{{ per_page }}"><input type="hidden" name="page" value="{{ pages }}">
           <button class="rounded-lg border border-slate-300 px-3 py-2 text-sm font-medium text-slate-700 hover:bg-slate-50">{{ pages }}</button>
         </form>
         {% endif %}
 
         <form method="get">
           <input type="hidden" name="q" value="{{ q }}">
-          <input type="hidden" name="category_id" value="{{ category_id or '' }}">
+          {% if category_id %}<input type="hidden" name="category_id" value="{{ category_id }}">{% endif %}
           <input type="hidden" name="recurrence_type" value="{{ recurrence_type }}">
           <input type="hidden" name="engagement_type" value="{{ engagement_type }}">
           <input type="hidden" name="per_page" value="{{ per_page }}">
diff --git a/app/modules/services/ui.py b/app/modules/services/ui.py
index 732afd2..cf4dde6 100644
--- a/app/modules/services/ui.py
+++ b/app/modules/services/ui.py
@@ -288,7 +288,17 @@ def category_edit_submit(request: Request, category_id: int, name: str = Form(..
 
 
 @router.get('/catalogue')
-def catalogue_list(request: Request, q: str = '', category_id: int | None = None, recurrence_type: str = '', engagement_type: str = '', page: int = 1, per_page: int = 20):
+def catalogue_list(request: Request, q: str = '', category_id: str = '', recurrence_type: str = '', engagement_type: str = '', page: int = 1, per_page: int = 20):
+    category_id_value: int | None = None
+    category_id_text = (category_id or '').strip()
+    if category_id_text:
+        try:
+            parsed_category_id = int(category_id_text)
+            if parsed_category_id > 0:
+                category_id_value = parsed_category_id
+        except (TypeError, ValueError):
+            category_id_value = None
+
     db = CommonSessionLocal()
     try:
         user = get_current_user(request, db=db)
@@ -296,7 +306,7 @@ def catalogue_list(request: Request, q: str = '', category_id: int | None = None
             return RedirectResponse(url='/login', status_code=303)
         if not _can_view_services(db, user):
             return _redirect_denied()
-        payload = list_catalogue_payload(db, q=q, category_id=category_id, recurrence_type=recurrence_type, engagement_type=engagement_type, page=page, per_page=per_page)
+        payload = list_catalogue_payload(db, q=q, category_id=category_id_value, recurrence_type=recurrence_type, engagement_type=engagement_type, page=page, per_page=per_page)
         tenant_id = _active_tenant_id(request, user)
         can_create_catalogue = _is_system_admin(db, user) and _has_perm(db, user, 'services.create')
         can_manage_firm_services = _can_manage_firm_services(db, user)